John (born on April 27, 1974) has health coverage for his son, Tony (born on May 25, 2000), provided by his employer with an 80 percent coinsurance provision and a $100 deductible. John's wife, Elizabeth (born on November 3, 1973), also has dependent coverage provided by her employer with an 80 percent coinsurance provision and a $500 deductible. Tony has a $1,000 medical bill that is covered by both policies. 

According to the coordination of benefits provision for group health insurance, how much Elizabeth's insurer will pay?